VALVE STEM SEALING

[NIELSKF]

I'm designing a manually operated shut-off valve.

I'm using stacked, teflon gaskets tightened into the valve body by a nut while surrounding the valve stem.

The gasket surface are made with an angle (60 deg) to the axis in order to increase the radial expansion when the temperature drops.

The assembly is leak tight a ambient temperature but leaks at -190 deg Celcius.

Who can give an input to the good design of such a gasket ??

Thanks in advance
Nielskf

 

[krecian]

you cant afford invisible leaks of gases at such low temperatures which expand nearly 600 times. Go for bellow-sealed valves.

KRECian

 

[scalleke]

I do not believe valve stem seals can operate good at these temperatures.

Why does this valve not have an extended bonnet that elevates the packing position to a point where there is no liquid but gas and the packing does not get cold and can properly seal?

Best Regards.

Scalleke